Radiosurgery and radiotherapy play an important role in the treatment of cancers. In general, radiosurgery and radiotherapy treatments consist of several phases. First, a precise three-dimensional (3D) map of the anatomical structures in the area of interest (head, body, etc.) is constructed to determine the exact coordinates of the contour within the anatomical structure, namely, to locate the tumor or abnormality within the body and define its exact shape and size. Second, a motion path for the radiation beam is computed to deliver a dose distribution that the surgeon finds acceptable, taking into account a variety of medical constraints. During this phase, a team of specialists develop a treatment plan using special computer software to optimally irradiate the tumor and minimize dose to the surrounding normal tissue by designing beams of radiation to converge on the contour area from different angles and planes. The third phase is where the radiation treatment plan is executed. During this phase, the radiation dose is delivered to the patient according to the prescribed treatment plan using radiation treatment techniques, such as intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT), for example.
These techniques are typically used with a radiotherapy system, such as a linear accelerator (linac), equipped with a multileaf collimator (MLC) to treat pathological anatomies (tumors, lesions, vascular malformations, nerve disorders, etc.) by delivering prescribed doses of radiation (X-rays, gamma rays, electrons, protons, particles, and/or ions) to the pathological anatomy while minimizing radiation exposure to the surrounding tissue and critical anatomical structures.
Accurate delineation, also known as segmentation or contouring, of targets, tumors, organs at risk (OAR), for example, is essential in treatment planning. Accurately delineating the targets, tumors, and organs at risk, is an important factor in preventing geographic misses in radiotherapy planning. For example, an underestimation of tumor extension will result in tumor recurrence. In contrast, overestimation of the tumor extension may increase unnecessary side effects.
Accurate delineation of contours requires the identification of anatomic borders of the contours such as tumors and OARs based on accurate diagnosis. Currently, delineation (contouring) can be done manually, semiautomatically, or automatically. While such “contouring” is typically reviewed by trained staff, a risk remains that errors are introduced and passed on to the next steps in the radiotherapy planning.